help with pan size!

It's basically a gingerbread that is a layer cake; you fill the cake with plum jam and then coat it in a chocolate ganache.

The recipe says use a 20 centimeter round cake pan. I am assuming an 8" round cake pan would suffice?

The question I have is it says to use an 8" deep round cake pan. How deep? It doesn't specify how deep the interior of the cake pan should be in inches. Can somebody help me with this please? Should it be 3" deep? 4" deep?